Bachelor's thesis offers an extensive and comprehensive as well as systematic insight into the war developments in time of preparation and execution of western invasion by Nazi war machine. At the beginning of the thesis there is a presentation of the way military strategists of German land forces tackled with tactical and operational problems, when they were developing and forming plans for the offensive in the West. After introducing the initial ideas and thoughts for the invasion, the primary focus of work follows: the performance of Erich von Manstein as well as creation, adoption and detailed description of essential characteristics of his invasion plan, which ultimately resulted in a highly successful and completely broken defensive sector of the allies. The first operational plans seemed to be too conventional, limited and they were not daring enough. Most of all, the earliest plans were far too similar to strategic ideas from the First World War. Even after some changes, they were still not satisfying enough. Continuous and prolonged period of bad and unstable weather, which was always one of the main reasons for many postponements of the offensive, gave Erich an opportunity to develop, improve and explain his alternative for the western invasion in the presence of Adolf Hitler. The result was almost revolutionary offensive idea, which transferred the main weight of German attack from classical northern part of the front to central sector. In other words: the main part of the invasion was shifted from the right army wing to its left. Instead of already used and tested frontal attack in Belgium - which would probably already had suffocated along the fortified defensive zone on the river Somme - the chief of staff of army group A suggested mysterious breakthrough through supposedly impassable and inaccessible region of Ardennes with Wehrmacht’s elite tank divisions. Consequently the area was very poorly protected. After the war, Manstein’s plan gained new title: “sickle cut” (in German: “Sichelschnitt”). His tactic was mainly based on the crucial moment of surprise, which Hitler wanted in his attacking options from the very beginning of designing different offensive alternatives for military march against the West. However, nobody actually knew how to deliver him that key moment until Manstein. In the final part of the thesis we tried to explain the issue of the theme that is linked to the question of why had Germany temporarily halted the unstoppable advance of German armour and tank units in front of the last port (Dunkirk), which by that time had not yet fallen into the hands of mighty Wehrmacht? This reckless act enabled the bulk of British expeditionary force successful evacuation and escape into neighbouring Great Britain.